The invention relates generally to the reading codes.
More particularly, the invention relates to the reading of bar codes on photographic material.
Bar codes in the form of so-called DX codes are reproduced on the margins of photographic films and provide information about the film manufacturer and the type of film. Some manufacturers now employ an extended DX code which, in addition, contains the respective image or frame numbers in encoded form. To allow reading and decoding of the encoded information, a clock track is arranged parallel to the data track containing such information.
The European patent application 331 049 discloses an apparatus having a film guide, and a reading device on either side of the film guide. Each reading device consists of two photosensors. With these reading devices, the encoded information and the clock track can be detected separately.
However, photographic films having the same format do not always have the same width so that the positions of the clock track and the data track relative to the photosensors can change. This can result in a certain degree of superposition, and thus in reading and interpretation errors.
In an attempt to eliminate this problem, the photosensors on one side of the guide have been mounted on a movable carrier whose position is automatically adjusted to the particular film width. This solution is, however, very complicated mechanically and consequently susceptible to errors. Moreover, it requires very much room.